My house has sockets in the walls with 3 holes, so I assumed it was earthed. Werongly, it turns out.One electrician says it would be hard to add the earth but he could do it.

Does anyone have any idea how much such a job would cost?

You've physically got to have a wire connected to each socket and appliance so to give you an idea if all the wires running from your consumer unit/electrical box are buried in cement all the wiring will need chasing out and re-installing/finishing the walls. If you've got surface mounted electrics in conduit or conduit buried in the walls it will be a bit easier.

Other than that bit of work above it's just a case of putting a rod in the garden and wiring that to your electric box.

You could always add an extra wire in surface mounted too but might look a bit ugly.

I got a circuit breaker (installed yesterday, which was earthed. seems the best solution unless you are in a 3rd story condo. We only have two pronged plugs.

I got a circuit breaker (installed yesterday, which was earthed. seems the best solution unless you are in a 3rd story condo. We only have two pronged plugs.

Er, that's not adding an earth, assuming it is an RCD / RCBO (has a test button) it is adding to your personal safety by reducing the possibility of an electric shock being fatal.

It will not stop your PC giving you a tingle.

Class-1 appliances still need a ground to operate safely, period!

To our OP:

Take the pragmatic approach, decide which outlets actually need a ground, i.e. will have 3-pin appliances connected, most will be in the kitchen and likely your PC.

To ground the ones that need it, if you can't get another wire in the conduit consider drilling through the wall behind the outlet and running your ground on the outside, next time you paint outside the wire will become all but invisible.

I would replace the un-grounded outlets with 2-pin 2 remind you they're not grounded.

I agree but that's not practical or sensible at the moment. Earthing the Safe t cut seemed like a good idea to me.